SSL problem when installing for whm/Cpanel

I am having trouble installing an SSL certificate I purchased into CPanel and WHM itself. The problem I am having is that I get connection timed out or similar in Firefox, and "Cannot find server" in IE. The certificate appears to install correctly. I installed it by going into WHM, clicking SSL/TLS (note, not Web SSL/TLS) and then selecting Change Server Certificates, selecting CPanel / WHM and entering the certificate information into the 3 text areas. The certificate verifies and it says "restarting ssl support". However, whenever I try to access the panels via SSL, it just will not work. The SSL certificate matches the hostname of the server, and the IP addresses resolve correctly. What could be wrong with it? I have since reformatted and reinstalled CPanel/WHM but to no avail... The supposed SSL certificate that is meant to come with Cpanel / WHM did not work either. Has anyone else experienced this? I have searched the forums but nothing that I have found seems to help.